Add dockerized CQL tools

[ivan-c]

• Add dockerized CQL toolchain, based on Maggie's notes

Run with:

docker-compose -f docker-compose.cql.yaml run --rm cql \
    ./cql-to-elm/build/install/cql-to-elm/bin/cql-to-elm \
        --format=JSON \
        --input=/opt/cql/r4/Factors_to_Consider_in_Managing_Chronic_Pain_FHIRv400.cql

Todo

• Add docs